The United States is considering pulling the plug on a landmark nuclear submarine deal with the UK and Australia, in what would be a devastating blow to the Aukus security alliance.

According to senior US defence officials, the Pentagon has launched a full-scale review of the 2021 pact, which promised to deliver nuclear-propelled submarines to Australia in a deal hailed as a key counter to Chinese aggression in the Indo-Pacific, reports The Telegraph.

The review is being spearheaded by Elbridge Colby, a former Trump campaign aide and current defence department official, who has long questioned the value of Aukus. Mr Colby has previously declared on social media that he was “sceptical” of the deal and suggested it could weaken America’s own submarine capabilities.

“In principle [Aukus is] a great idea. But I’ve been very sceptical in practice. I remain sceptical – agnostic as I put it to [The Sydney Morning Herald] – but more inclined based on new information I’ve gleaned,” he wrote. “It would be crazy to have fewer [attack submarines] in the right place and time.”

The pact, signed with great fanfare in 2021, includes a commitment from the US to supply Australia with at least eight nuclear-powered submarines, with the UK contributing Rolls-Royce-built pressurised water reactors and naval training.

But there are growing fears in Washington that the $235 billion investment over 30 years could undermine America's own defence capabilities, as US shipyards struggle to meet demand.

The US Navy currently operates 24 Virginia-class submarines, the same class Australia hopes to acquire, but production has lagged behind the Pentagon’s two-per-year target.

Critics now question whether the US should be exporting these subs at all, before it has fully equipped its own fleet.

The agreement not only covers submarines but also includes cyber warfare development, artificial intelligence, and hypersonic missiles—all aimed at bolstering Western influence in the Indo-Pacific.

On Tuesday, Defence Secretary Pete Hegseth sought to calm nerves, stating the US would honour its commitment to supply nuclear-powered submarines to Australia, despite internal divisions.

The pact has not been without controversy. It froze out France from a lucrative submarine contract with Australia, prompting a major diplomatic row in 2021.

A British government spokesman told The Telegraph that it was aware of the review and was stressing the strategic value of the deal to its American allies.

The spokesman said: “Aukus is a landmark security and defence partnership with two of our closest allies.

“It is one of the most strategically important partnerships in decades, supporting peace and security in the Indo-Pacific and Euro-Atlantic, while also delivering jobs and economic growth in communities across all three nations.”